Sharif Digital Repository

Monumental structures are cultural and aesthetic bases in every nation, and our duty to maintaining these valuable remnants is obvious clearly. Meanwhile, the vaults have essential role as main elements in the Islamic architecture, and evaluation of their performance as well as retrofitting with regard to placing in earthquake-prone regions has high importance. Therefore, in this dissertation, performance of spherical and pointed domes are evaluated. Hence, 13 traditional Iranian domes are modeled with linear and non-linear material behavior in ABAQUS finite element software to verifying effect of their geometries in seismic performance. Base on Complex behavior of these models, they... 

Endurance Time (ET) method is a dynamic analysis method in which the structure is subjected to an intensifying accelerogram and its response is recorded at different times.On the other hand a new method for designing earthquake resistant structures is Performance-Based Design (P-BD) method. P-BD is a methodology in which structural design criteria are expressed in terms of achieving a set of different performance objectives. In this research the application of ET method and target curve (which is defined based on ET method concepts) in the performance-based design has been studied.Correlating time in ET method and earthquake return period, the design,assessment and retrofitting of different... 

In Endurance Time method structures are subjected a set of predesigned intensifying excitations. These excitations are produced in a way that their response spectrum, while complying with a specified spectrum, intensifies with time. So they can be used approximately to simulate the average effects of several ground motions scaled to different intensities. In this study applicability of Endurance Time method for evaluating collapse potential of buildings is investigated. A set of steel moment frames is used for collapse assessment. The process of using Endurance Time method in collapse evaluation is explained with consideration of uncertainty effects. collapse fragility curves and collapse... 

Study of dams' behavior and their safety against earthquakes has been interesting due to the high rate of failure. In the past, this study was just about linear analysis of dams. However, the weakness of concrete in tensile strength results in cracks in body of dams. Therefore, the nonlinear analysis of these huge structures seems to be so important. Many researches have been done in this field to model dam-reservoir-foundation with effects of concrete nonlinearity. In spite of the fact that gravity dams' safety depends on cracking status and consequently on nonlinear behavior of concrete, we cannot reach accurate and suitable results for dynamic behavior of concrete dams because these... 

Endurance Time (ET) method is a relatively general analysis method based on time history analysis for evaluation of structure systems under dynamic excitations resulted from earthquakes. Assessment criterion in this method is based on time of endurance of structure versus applied acceleration function and don't use parameters such as stiffness, lateral strength, period of structure and other dynamic characteristics straightly. Upper time of endurance means better operation. In this method, if assumed damage index stays under allowable limit until determined time of endurance then the structure assumed acceptable. In this study, nonlinear analysis of anchored and unanchored (on rigid base)... 

This study has been carried out for investigating the need for an appropriate and fast seismic analysis method to be applied in performance based design (PBD), and show the application of Endurance Time (ET) method and its advantages in PBD. The major goal of this project is analysis and study of behavior of concrete frames with retrofitted shear walls with FRP by ET method with acceleration functions which are compatible with actual earthquake and comparation with time history analysis, forand comparation of whole results with shear wall frames that are not retrofitted. Performance criteria of FEMA code were used fore comparation of two frame categories (retrofitted and not retrofitted).... 

The AISC Seismic Design Provisions include capacity design requirements for steel plate shear walls since 2005. This system consist of thin web plates that infill frame panels with steel beams as horizontal boundary elements (HBEs), and columns as vertical boundary elements (VBEs). The thin unstiffened web plates are expected to buckle in shear at low load levels and develop tension field action, providing ductility and energy dissipation through tension yielding of the web plate. HBEs are designed for stiffness and strength requirements and are expected to anchor the tension field formation in the web plates. VBEs are designed for yielding of web plates and plastic hinge formation at the... 

The actual value of structures should not be evaluated only based on initial cost, because failure cost and economical losses due to corrosion and natural hazards can be catastrophic. When a long life Performance of a structure is expected, life cycle cost analysis is the best way to assess and compare economic value of different design choices. The main purpose of this work is investigating the effect of shear walls in limit state cost and total cost . Results demonstrate that shear walls can reduce limit state cost up to 70 percent . Furthermore the influence of increasing thickness of shear walls and effect of reducing dead loads in total life cycle cost is discussed. It is shown that... 

Endurance Time Method (ET) is a dynamic analysis based on the Time History Analysis in which a predefined intensifying excitation would be applied to the structure and then the performance of the structure would be assessed based on the maximum time that the structure could fulfill the predefined criteria. This method has less complications than the other ordinary Time History methods and decreases the calculations. This method could be applied to Seismic Isolated Structures. Seismic Isolation is a method for decreasing seismic response of structures without increasing strength and ductility of the structure. In this Method all or parts of the structure would be separated from the ground... 

This project aims at the calculation of response distribution of a structure using Endurance Time Analysis (ETA). The traditional approach for this calculation is Incremental Dynamic Analysis (IDA). One of the drawbacks of the IDA is its excessive computational complexity. In the ETA, the structure is analyzed using a set of artificial ground motions with increasing intensities as time passes. As a result, the ETA can be used to calculate the response distribution of the structure in a range of intensities. In the traditional ETA, only the median of the response is calculated. In this study, the response distribution is calculated as well as the median. To achieve this, the proposed approach... 

Metallic implants are often used in the open reduction and internal fixation of fractures. Open reduction and internal fixation are commonly used in cases of trauma when the bone cannot be healed using external methods such as casting. The locking compression plate combines the conventional screw holes, which use non-locking screws, with locking screw holes, which use locking head screws. This allows for more versatility in the application of the plate.
In the present work, the stress (von-mises) and deformation of a locking compression plate fixed across a transverse fracture (2-mm gap) at the midshaft of femur was evaluated by Ansys software. Femur model is divided to two part... 

Researches in last decades have shown that biological cell’s functionality is related to the way of their deformation in response to forces and stresses exerted on the cell. Therefore designing microsensors with easy and economical applicationswhich are capable for determining cell mechanical properties seems to be logical. In this project using an electrostatically actuated microbeam with both clamped ends equipped with an indenter at midpoint to transmit force on the cell, proposed as a technique to apply axial load on the cell. Inthis research by implementation of approximated methods for solving nonlinear algebraic and differential equations, governing on microbeam deflection, it has... 

Since the early 1980s, it is well-known that the dynamic properties of structures are effected by flexibility of the underlying soil due to Soil-Structure Interaction (SSI). As a result, the soil-structure systems usually has a longer natural period and higher damping ratio that structure would have in the fixed-base state. The importance of SSI effect as well as the complexity of the phenomenon have made it the subject of several researches for the last four decades. It also has found its way into some seismic codes and provisions as simplified guidelines.In the present paper, a simplified 3DOF model is suggested as the soil-structure system by replacing the structure by a SDOF model using... 

Stratified flows are common in natural systems such as the oceans and the atmosphere. The hydraulics of two-layer flow over an obstacle, which helps with understanding and control of these flows, has been studied by many researchers. However, a type of two-layer flow, called the Approach-controlled flow, has not yet been fully understood, and there are ambiguities about it. Having considerable nonhydrostatic pressure in the so-called supercritical leap region, this flow type cannot be explained even qualitatively without accounting for the nonhydrostatic pressure. Also, the composite Froude number which is defined based on the hydrostatic pressure assumption for two-layer flows, is not...